I have written following code using dynamic programming technique, can i use ArrayList here .Please let me know if i can improve this code.

I have written the following code using a dynamic programming technique. Can I use ArrayList here? Please let me know if I can improve this code.

package com.java.fib;

import java.math.BigInteger;
import java.util.HashMap;

public class Fibonaci {

    public static void main(String[] args) {
        System.out.println(" number ");
        long startTime = System.currentTimeMillis();
        HashMap<Integer, BigInteger> memoized = new HashMap<Integer, BigInteger>();
         fibonanci(220, memoized);
        System.out.println(" Total Time "
                + (System.currentTimeMillis() - startTime));
    }

    private static BigInteger fibonanci(int n, HashMap<Integer, BigInteger> memoized) {
        if (memoized.containsKey(n)) {
            return memoized.get(n);
        }
        if (n <= 0) {
             return BigInteger.ZERO;
        }
        if (n <= 2) {
            return BigInteger.ONE;
        } else {
            BigInteger  febonani = fibonanci(n - 1, memoized).add (fibonanci(n - 2, memoized));
            System.out.println(" febonani " + febonani);
                memoized.put(n, febonani);
            return febonani;
        }
    }
}